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 * Copyright (c) 2024 unknowIfGuestInDream.
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 * notice, this list of conditions and the following disclaimer.
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 * names of its contributors may be used to endorse or promote products
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package com.tlcsdm.core.javaluator;

import com.fathzer.soft.javaluator.AbstractEvaluator;
import com.fathzer.soft.javaluator.Operator;
import com.fathzer.soft.javaluator.Parameters;

import java.util.Iterator;

/**
 * An example of how to implement an evaluator from scratch.
 *
 * @author unknowIfGuestInDream
 */
public class SimpleBooleanEvaluator extends AbstractEvaluator<Boolean> {
    /**
     * The negate unary operator.
     */
    public static final Operator NEGATE = new Operator("!", 1, Operator.Associativity.RIGHT, 3);
    /**
     * The logical AND operator.
     */
    private static final Operator AND = new Operator("&&", 2, Operator.Associativity.LEFT, 2);
    /**
     * The logical OR operator.
     */
    public static final Operator OR = new Operator("||", 2, Operator.Associativity.LEFT, 1);

    private static final Parameters PARAMETERS;

    static {
        // Create the evaluator's parameters
        PARAMETERS = new Parameters();
        // Add the supported operators
        PARAMETERS.add(AND);
        PARAMETERS.add(OR);
        PARAMETERS.add(NEGATE);
    }

    public SimpleBooleanEvaluator() {
        super(PARAMETERS);
    }

    @Override
    protected Boolean toValue(String literal, Object evaluationContext) {
        return Boolean.valueOf(literal);
    }

    @Override
    protected Boolean evaluate(Operator operator, Iterator<Boolean> operands, Object evaluationContext) {
        if (operator == NEGATE) {
            return !operands.next();
        } else if (operator == OR) {
            Boolean o1 = operands.next();
            Boolean o2 = operands.next();
            return o1 || o2;
        } else if (operator == AND) {
            Boolean o1 = operands.next();
            Boolean o2 = operands.next();
            return o1 && o2;
        } else {
            return super.evaluate(operator, operands, evaluationContext);
        }
    }
}
